Put the Oreo and Digestives biscuits in the food processor and blitz until they become crumbs. Then add the 125g melted butter to biscuit crumbs and process again until well mixed. It should be firm to touch and hold its shape when squashed together.
Press the biscuit and butter mixture evenly and firmly into the base of the baking tin.
Next, dissolve the contents of two Bondi Chai Club Cinnamon Sachets in 1 tbsp of hot water, then pour into a clean food processor.
Add Philadelphia cream cheese, sour cream, sugar and eggs to the food processor and blend until well mixed. Pour onto biscuit base and sprinkle some cinnamon powder on top if you want to.
Bake for 45 minutes or until partially firm to touch. If it is too firm it has been overcooked. The surface should still be a tiny bit wobbly.